The present invention relates generally to the field of dentistry and, in particular, to and new and useful dental post for supporting a tooth replacement on a natural tooth root, the tooth root having a hollow canal from which a nerve has been removed, the canal having an outer opening and the root having a non-round counter-sink at the top of the tooth root which communicate with the canal opening.
A wide variety of posts are known for use in supporting tooth replacements such as crowns, bridges or other structures above a patients gum line. The posts are usually made of strong metal and have shanks that extend in, and are cemented to hollow root canals prepared by the dentist by drilling out the dead root and other tissue from a damaged tooth.
Although usually made entirely rigid, a flexible post is disclosed by U.S. Pat. No. 5,919,044 to Sicurelli, Jr. et al. This flexible post is made from fiberglass or optical fibers suitable for medical use. U.S. Pat. No. 6,135,775 to Weisman also discloses a post made of plastic.
A dental post with a tapered, polygonal cross-section is disclosed in U.S. Pat. No. 347,975 to Starr. U.S. Pat. No. 403,428 to Hansen discloses an artificial tooth plug having a conical shank with threads for inserting into a tooth root and a larger diameter collar around the base. The collar provides protection over the root but does not extend into the root.
U.S. Pat. No. 616,302 to Evans discloses a post and disk for attaching crowns. The post is secured inside the root socket and the disk, which has a larger diameter than the post, prevents downward movement and supports an artificial tooth externally. U.S. Pat. No. 984,782 to Starr teaches a crown pin having a generally cylindrical lower portion with a flattened side and a perpendicular plate at one end that also extends over a tooth root. Also see U.S. Pat. Nos. 1,109,080 and 1,479,508, for other dental post structures.
A dental post having a polygonal perimeter for the crown but not for the tooth root, is disclosed in U.S. Pat. No. 1,589,994 to Simmons. U.S. Pat. No. 3,508,334 to Weissman disclosed a guide post with flange and drill guides but is not meant to be a permanent part of the patients dental work. U.S. Pat. No. 4,427,383 to Goldman teaches a tooth reconstruction having a threaded screw and a hex nut which is inside and supports an artificial tooth. U.S. Pat. No. 4,449,937 to Weissman shows a dental anchor having a threaded implant portion, a flange and a square anchoring portion secured to the opposite side of the flange. The flange is intended to prevent further movement into a tooth root canal, while the anchoring portion prevents rotation of a dental prosthesis connected using the anchor. These parts of the post are in the crown and not the tooth root.
Also see U.S. Pat. Nos. 4,543,065 and 4,588,381. U.S. Pat. No. 4,600,391 to Jacob teaches a cylindrical countersink flange for being seated in a cylindrical countersink at the top of a tooth root canal. This structure does not and cannot not resist rotation of the post in the root since rotation is, in fact, necessary to install this threaded post. A cylindrical, and therefore rotatable, countersink is also taught by U.S. Pat. No. 5,348,476 to Cohen et al.
See U.S. Pat. No. 4,759,714 to Szegvary which discloses a post with threaded shank post that is fixed into the root with the ususal composite cement, and an upper crown supporting portion with rigid side ribs for extending into the luting cement inside a crown. Other posts with threads of other structures to help secure the post shank are disclosed in U.S. Pat. Nos. 4,778,388; 4,846,685; 5,066,230 and 5,326,263.
A need remains for an improved post which will not rotate in the root and which securely supports a tooth replacement.
It is an object of the present invention to provide a dental post and method for supporting a tooth replacement on a natural tooth root having a hollow canal from which a nerve has been removed, which provides a non-round countersink at the top of the tooth root, communicating with the canal opening.
Another object of the invention is to provide a post having a shank with a first root engagement portion for extending into the hollow canal, and a second tooth replacement support portion for extending out of the canal. The post has a non-round flange formed as one piece with the shank on the first portion but adjacent the second portion, the non-round flange being adapted to be received in the non-round countersink for precluding relative rotation between the post and the root when the first root engagement portion is in the root.
Another object of the invention is to provide a dental post including at least one flexible flange formed as one piece with the shank and extending outwardly from either the first or the second portions of the shank, or both. According to another object of the invention, two to three flexible flanges extend outwardly from the first root engagement portion in the root and two to three such flanges also extend outwardly from the second, tooth replacement receiving or support portion of the shank.
A still further object of the invention is to manufacture the post entirely of a suitably strong and biocompatible plastic that is capable of being cemented to the root and to which a crown or other tooth replacement can be cemented.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.